الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
The proliferation of harmonic currents in the electrical networks is one of the most serious challenges that encounter the electrical power industry. Failure to respond to such a challenge will have perilous repercussions. Different solutions were presented, nonetheless active filters have proven themselves to be the most effective, dynamic and self adaptive solution. The most popular active filter topology is the shunt active filter. A shunt active filter generally comprises a controller and a power converter with a dc-side capacitor. Due to the voltage and power rating limitations of power electronic switches, traditional two-level converters are being replaced by different multilevel topologies in medium and high power applications. And so, multilevel inverter configurations are being deployed in medium and high power active filters. The three-level neutral point clamp inverter is a very attractive topology for implementing shunt active filters in medium and high power networks. However, the performance of the neutral point clamp inverter depends on the regulation of the neutral point potential. A control algorithm is proposed for the three-level neutral point clamp inverter based active filter. It employs three independent ADAptive LINEar combiner (ADALINE) modules to provide fast, accurate and adaptive harmonic tracking. Two PI controllers are implemented to generate the necessary reference current components for regulating the neutral point potential and the dc-side voltage, simultaneously. These reference components are added to the estimated harmonic signal to obtain the reference compensation current of the active filter. A dual band hysteresis current control technique is utilized to generate the inverter gating signals necessary to inject the reference compensation current. Furthermore, the proposed control algorithm is easily adapted to extend its application to the three-level flying-capacitor inverter based active filters.EMTDC/PSCAD simulation package is used to model the proposed systems. Different test cases are conducted to study the dynamic performance of the proposed control algorithms for the active filter based on the neutral point clamp and the flying-capacitor inverters. The simulation results expose the success of the multifunction control algorithms under normal and dynamic conditions. The accurate and adaptive compensation of the load current harmonics is achieved. Moreover, fast regulation of the dc-side voltage is achieved simultaneously with the balancing of the voltage across the dc-side capacitors in the neutral point clamp inverter, as well as the clamping capacitor in the flying-capacitor inverter topologies.